Parasites of hoki, Macruronus magellanicus, in the Southwest Atlantic and Southeast Pacific Oceans, with an assessment of their potential value as biological tags

The aims of the present study were to investigate the protozoan and metazoan parasite fauna of hoki Macruronus magellanicus in the Southwest Atlantic and Southeast Pacific and to identify parasites of potential value as biological tags for stock identification and migrations. In 2007 a total of 76 hoki were examined from three locations, two off the coast of Chile and one off the Falkland Islands. Two further samples were taken in 2009, one of 32 hoki taken from a position off the coast of Chile between those sampled in 2007 and one of 42 juvenile hoki taken off the Falkland Islands. Seventeen different parasite taxa were recorded, including eight identified to species. Seven were new host records for hoki, and at least three, and possibly as many as five, are new species. The most promising tag parasites for hoki stock identification are the long-lived larvae of the cestodes Hepatoxylon trichiuri and Pseudophyllidea gen. sp. and of the nematode Anisakis sp. Three others - the myxosporean Myxidium baueri, the nematode Pseudascarophis sp. and the acanthocephalan Echinorhynchus longiproboscis - were identified as potentially useful for following seasonal migrations of hoki and for estimating the proportions of fish of different origin in mixed samples.